The present invention relates to a method for moving cartridges between library strings. More specifically, the present invention relates to a method for selecting a relay-point library string to execute cartridge mounting requests more efficiently when a plurality of library strings (LS) are connected by using shuttle connections.
A shuttle complex has been proposed for libraries in which a plurality of library strings that connect a plurality of libraries with storage media such as tapes are arranged in rows. This shuttle complex is a storage library in which library strings are connected by shuttle connections (SC) (IBM System Storage TS3500, etc.). In this shuttle complex, cars are able to move within a shuttle connection and are used to move (or transport) cartridges including storage media such as tapes between library strings and to mount the tapes in a tape drive (drive) or store them in a slot within the library frame specified as the destination point.
Due to phased scale-up that uses groups of libraries with a large-scale shuttle configuration, shuttle connections directly connected to all library strings cannot be guaranteed. There are shuttle complexes in which a cartridge cannot be transported in response to a mounting request except via two or more shuttle connections and a library string serving as a relay point (relay-point library string). When there are shuttle connections that do not directly connect two library strings, the selection of a relay-point library string can affect the performance of writing and reading data on a cartridge.
In a shuttle complex by using two or more shuttle connections, the transport of cartridges via the shuttles takes more time than moving a cartridge within a tape library. When a cartridge is moved via a relay point, the random selection of a relay-point library string is not ideal from the standpoint of performance when moving cartridges.